Semiconductor package for thermal dissipation

ABSTRACT

A first package is bonded to a first substrate with first external connections and second external connections. The second external connections are formed using materials that are different than the first external connections in order to provide a thermal pathway from the first package. In a particular embodiment the first external connections are solder balls and the second external connections are copper blocks.

PRIORITY CLAIM AND CROSS-REFERENCE

This application is a divisional and claims the benefit of U.S. patentapplication Ser. No. 14/321,365, filed on Jul. 1, 2014, and entitled“Semiconductor Package for Thermal Dissipation,” which application ishereby incorporated by reference.

BACKGROUND

Since the invention of the integrated circuit (IC), the semiconductorindustry has experienced rapid growth due to continuous improvements inthe integration density of various electronic components (i.e.,transistors, diodes, resistors, capacitors, etc.). For the most part,this improvement in integration density has come from repeatedreductions in minimum feature size, which allows more components to beintegrated into a given area.

These integration improvements are essentially two-dimensional (2D) innature, in that the volume occupied by the integrated components isessentially on the surface of the semiconductor wafer. Although dramaticimprovement in lithography has resulted in considerable improvement in2D IC formation, there are physical limits to the density that can beachieved in two dimensions. One of these limits is the minimum sizeneeded to make these components. Also, when more devices are put intoone chip, more complex designs are utilized.

In an attempt to further increase circuit density, three-dimensional(3D) ICs have been investigated. In a typical formation process of a 3DIC, two dies are bonded together and electrical connections are formedbetween each die and contact pads on a substrate. For example, oneattempt involved bonding two dies on top of each other. The stacked dieswere then bonded to a carrier substrate and wire bonds electricallycoupled contact pads on each die to contact pads on the carriersubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a first package in accordance with some embodiments.

FIGS. 2A-2B illustrate a second package in accordance with someembodiments.

FIG. 3 illustrates a bonding of the first package to the second packagein accordance with some embodiments.

FIGS. 4A-4C illustrate a bonding of the second package using externalconnections to a substrate in accordance with some embodiments.

FIG. 5 illustrates a flow of heat in accordance with some embodiments.

FIG. 6 illustrates slots within the external connections in accordancewith some embodiments.

FIG. 7 illustrates an embodiment using balls for the externalconnections in accordance with some embodiments.

FIG. 8 illustrates placements of the external connections in accordancewith some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

With reference now to FIG. 1, there is shown a first package 100. Thefirst package 100 may comprise a first substrate 103, a firstsemiconductor device 101, first contact pads 109, a first encapsulant111, and first external connections 113. In an embodiment the firstsubstrate 103 may be, e.g., a packaging substrate comprising internalinterconnects to connect the first semiconductor device 101 to otherexternal devices such as a second package 200 (not illustrated in FIG. 1but illustrated and described below with respect to FIGS. 2A-2B).

Alternatively, the first substrate 103 may be an interposer used as anintermediate substrate to connect the first semiconductor device 101 tothe other external devices. In this embodiment the first substrate 103may be, e.g., a silicon substrate, doped or undoped, or an active layerof a silicon-on-insulator (SOI) substrate. However, the first substrate103 may alternatively be a glass substrate, a ceramic substrate, apolymer substrate, or any other substrate that may provide a suitableprotection and/or interconnection functionality. These and any othersuitable materials may alternatively be used for the first substrate103.

The first semiconductor device 101 may be a semiconductor devicedesigned for an intended purpose such as being a logic die, a centralprocessing unit (CPU) die, a memory die, combinations of these, or thelike. In an embodiment the first semiconductor device 101 comprisesintegrated circuit devices, such as transistors, capacitors, inductors,resistors, first metallization layers (not shown), and the like,therein, as desired for a particular functionality. In an embodiment thefirst semiconductor device 101 is designed and manufactured to work inconjunction with or concurrently with a second semiconductor device 211(not illustrated in FIG. 1 but illustrated and described below withrespect to FIGS. 2A-2B).

The first contact pads 109 may be formed on the first substrate 103 toform electrical connections between the first semiconductor device 101and, e.g., first external connections 113. In an embodiment the firstcontact pads 109 may be formed over and in electrical contact withelectrical routing (not separately illustrated in FIG. 1) within thefirst substrate 103. The first contact pads 109 may comprise aluminum,but other materials, such as copper, may alternatively be used. Thefirst contact pads 109 may be formed using a deposition process, such assputtering, to form a layer of material (not shown) and portions of thelayer of material may then be removed through a suitable process (suchas photolithographic masking and etching) to form the first contact pads109. However, any other suitable process may be utilized to form thefirst contact pads 109. The first contact pads 109 may be formed to havea thickness of between about 0.5 μm and about 4 μm, such as about 1.45μm.

The first encapsulant 111 may be used to encapsulate and protect thefirst semiconductor device 101 and the first substrate 103. In anembodiment the first encapsulant 111 may be a molding compound and maybe placed using a molding device (not illustrated in FIG. 1). Forexample, the first substrate 103 and the first semiconductor device 101may be placed within a cavity of the molding device, and the cavity maybe hermetically sealed. The first encapsulant 111 may be placed withinthe cavity either before the cavity is hermetically sealed or else maybe injected into the cavity through an injection port. In an embodimentthe first encapsulant 111 may be a molding compound resin such aspolyimide, PPS, PEEK, PES, a heat resistant crystal resin, combinationsof these, or the like.

Once the first encapsulant 111 has been placed into the cavity such thatthe first encapsulant 111 encapsulates the region around the firstsubstrate 103 and the first semiconductor device 101, the firstencapsulant 111 may be cured in order to harden the first encapsulant111 for optimum protection. While the exact curing process is dependentat least in part on the particular material chosen for the firstencapsulant 111, in an embodiment in which molding compound is chosen asthe first encapsulant 111, the curing could occur through a process suchas heating the first encapsulant 111 to between about 100° C. and about130° C., such as about 125° C. for about 60 sec to about 3000 sec, suchas about 600 sec. Additionally, initiators and/or catalysts may beincluded within the first encapsulant 111 to better control the curingprocess.

However, as one having ordinary skill in the art will recognize, thecuring process described above is merely an exemplary process and is notmeant to limit the current embodiments. Other curing processes, such asirradiation or even allowing the first encapsulant 111 to harden atambient temperature, may alternatively be used. Any suitable curingprocess may be used, and all such processes are fully intended to beincluded within the scope of the embodiments discussed herein

In an embodiment the first external connections 113 may be formed toprovide an external connection between the first substrate 103 and,e.g., second external connections 203 (not illustrated in FIG. 1 butillustrated and described below with respect to FIGS. 2A-2B). The firstexternal connections 113 may be contact bumps such as microbumps orcontrolled collapse chip connection (C4) bumps and may comprise amaterial such as tin, or other suitable materials, such as silver orcopper. In an embodiment in which the first external connections 113 aretin solder bumps, the first external connections 113 may be formed byinitially forming a layer of tin through any suitable method such asevaporation, electroplating, printing, solder transfer, ball placement,etc, to a thickness of, e.g., about 100 μm. Once a layer of tin has beenformed on the structure, a reflow is performed in order to shape thematerial into the desired bump shape.

FIG. 2A illustrates an intermediate product in a process of forming,e.g., a second package 200, such as an integrated fan out (InFO)package. As illustrated in FIG. 2A, the intermediate structure comprisesa carrier substrate 201, an adhesive layer 202, a polymer layer 205, aseed layer 207, vias 209, a second semiconductor device 211, a secondencapsulant 213, a first redistribution layer 215, second contact pads217, a first passivation layer 219, and second external connections 203.The carrier substrate 201 comprises, for example, silicon basedmaterials, such as glass or silicon oxide, or other materials, such asaluminum oxide, combinations of any of these materials, or the like. Thecarrier substrate 201 is planar in order to accommodate an attachment ofsemiconductor devices such as the second semiconductor device 211.

The adhesive layer 202 is placed on the carrier substrate 201 in orderto assist in the adherence of overlying structures (e.g., the polymerlayer 205). In an embodiment the adhesive layer 202 may comprise anultra-violet glue, which loses its adhesive properties when exposed toultra-violet light. However, other types of adhesives, such as pressuresensitive adhesives, radiation curable adhesives, epoxies, combinationsof these, or the like, may also be used. The adhesive layer 202 may beplaced onto the carrier substrate 201 in a semi-liquid or gel form,which is readily deformable under pressure.

The polymer layer 205 is placed over the adhesive layer 202 and isutilized in order to provide protection to, e.g., the secondsemiconductor device 211 once the second semiconductor device 211 hasbeen attached. In an embodiment the polymer layer 205 may bepolybenzoxazole (PBO), although any suitable material, such as polyimideor a polyimide derivative, may alternatively be utilized. The polymerlayer 205 may be placed using, e.g., a spin-coating process to athickness of between about 2 μm and about 15 μm, such as about 5 μm,although any suitable method and thickness may alternatively be used.

The seed layer 207 is a thin layer of a conductive material that aids inthe formation of a thicker layer during subsequent processing steps. Theseed layer 207 may comprise a layer of titanium about 1,000 Å thickfollowed by a layer of copper about 5,000 Å thick. The seed layer 207may be created using processes such as sputtering, evaporation, or PECVDprocesses, depending upon the desired materials. The seed layer 207 maybe formed to have a thickness of between about 0.3 μm and about 1 μm,such as about 0.5 μm.

Once the seed layer 207 has been formed, a photoresist (not illustratedin FIG. 2A) may be placed and patterned over the seed layer 207. In anembodiment the photoresist may be placed on the seed layer 207 using,e.g., a spin coating technique to a height of between about 50 μm andabout 250 μm, such as about 120 μm. Once in place, the photoresist maythen be patterned by exposing the photoresist to a patterned energysource (e.g., a patterned light source) so as to induce a chemicalreaction, thereby inducing a physical change in those portions of thephotoresist exposed to the patterned light source. A developer is thenapplied to the exposed photoresist to take advantage of the physicalchanges and selectively remove either the exposed portion of thephotoresist or the unexposed portion of the photoresist, depending uponthe desired pattern.

In an embodiment the pattern formed into the photoresist is a patternfor the vias 209. The vias 209 are formed in such a placement as to belocated on different sides of subsequently attached devices such as thesecond semiconductor device 211. However, any suitable arrangement forthe pattern of vias 209 may alternatively be utilized.

Once the photoresist has been patterned, the vias 209 are formed withinthe photoresist. In an embodiment the vias 209 comprise one or moreconductive materials, such as copper, tungsten, other conductive metals,or the like, and may be formed, for example, by electroplating,electroless plating, or the like. In an embodiment, an electroplatingprocess is used wherein the seed layer 207 and the photoresist aresubmerged or immersed in an electroplating solution. The seed layer 207surface is electrically connected to the negative side of an external DCpower supply such that the seed layer 207 functions as the cathode inthe electroplating process. A solid conductive anode, such as a copperanode, is also immersed in the solution and is attached to the positiveside of the power supply. The atoms from the anode are dissolved intothe solution, from which the cathode, e.g., the seed layer 207, acquiresthe dissolved atoms, thereby plating the exposed conductive areas of theseed layer 207 within the opening of the photoresist.

Once the vias 209 have been formed using the photoresist and the seedlayer 207, the photoresist may be removed using a suitable removalprocess. In an embodiment, a plasma ashing process may be used to removethe photoresist, whereby the temperature of the photoresist may beincreased until the photoresist experiences a thermal decomposition andmay be removed. However, any other suitable process, such as a wetstrip, may alternatively be utilized. The removal of the photoresist mayexpose the underlying portions of the seed layer 207.

After the removal of the photoresist exposes the underlying seed layer207, these portions are removed. In an embodiment the exposed portionsof the seed layer 207 (e.g., those portions that are not covered by thevias 209) may be removed by, for example, a wet or dry etching process.For example, in a dry etching process reactants may be directed towardsthe seed layer 207, using the vias 209 as masks. Alternatively, etchantsmay be sprayed or otherwise put into contact with the seed layer 207 inorder to remove the exposed portions of the seed layer 207. After theexposed portion of the seed layer 207 has been etched away, a portion ofthe polymer layer 205 is exposed between the vias 209.

After the vias 209 have been formed, the second semiconductor device 211may be placed on the exposed polymer layer 205. In an embodiment thesecond semiconductor device 211 may be similar to the firstsemiconductor device 101, such as by being a logic die, a memory die, aCPU die, combinations of these, or the like. In an embodiment the secondsemiconductor device 211 is designed and manufactured to work eitherwith or concurrently with the first semiconductor device 101. The secondsemiconductor device 211 may be attached to the polymer layer 205 using,e.g., an adhesive material, although any suitable method of attachmentmay alternatively be utilized.

In an embodiment the second semiconductor device 211 comprises a secondsubstrate 221, active devices (not separately illustrated), secondmetallization layers 223, a second passivation layer 225, and secondcontact pads 227. The second substrate 221 may comprise bulk silicon,doped or undoped, or an active layer of a silicon-on-insulator (SOI)substrate. Generally, an SOI substrate comprises a layer of asemiconductor material such as silicon, germanium, silicon germanium,SOI, silicon germanium on insulator (SGOI), or combinations thereof.Other substrates that may be used include multi-layered substrates,gradient substrates, or hybrid orientation substrates.

The active devices within the second semiconductor device 211 comprise awide variety of active devices and passive devices such as capacitors,resistors, inductors and the like that may be used to generate thedesired structural and functional desires of the design for the secondsemiconductor device 211. The active devices within the secondsemiconductor device 211 may be formed using any suitable methods eitherwithin or else on the second substrate 221.

The second metallization layers 223 are formed over the second substrate221 and the active devices within the second semiconductor device 211and are designed to connect the various active devices within the secondsemiconductor device 211 to form functional circuitry. In an embodimentthe second metallization layers 223 are formed of alternating layers ofdielectric and conductive material and may be formed through anysuitable process (such as deposition, damascene, dual damascene, etc.).In an embodiment there may be four layers of metallization separatedfrom the second substrate 221 by at least one interlayer dielectriclayer (ILD), but the precise number of second metallization layers 223is dependent upon the design of the second semiconductor device 211.

The second contact pads 227 may be formed over and in electrical contactwith the second metallization layers 223. The second contact pads 227may comprise aluminum, but other materials, such as copper, mayalternatively be used. The second contact pads 227 may be formed using adeposition process, such as sputtering, to form a layer of material (notshown) and portions of the layer of material may then be removed througha suitable process (such as photolithographic masking and etching) toform the second contact pads 227. However, any other suitable processmay be utilized to form the second contact pads 227. The second contactpads 227 may be formed to have a thickness of between about 0.5 μm andabout 4 μm, such as about 1.45 μm.

The second passivation layer 225 may be formed on the second substrate221 over the second metallization layers 223 and the second contact pads227. The second passivation layer 225 may be made of one or moresuitable dielectric materials such as silicon oxide, silicon nitride,low-k dielectrics such as carbon doped oxides, extremely low-kdielectrics such as porous carbon doped silicon dioxide, combinations ofthese, or the like. The second passivation layer 225 may be formedthrough a process such as chemical vapor deposition (CVD), although anysuitable process may be utilized, and may have a thickness between about0.5 μm and about 5 μm, such as about 9.25 KÅ. Once in place the secondcontact pads 227 may be exposed by removing a portion of the secondpassivation layer 225 through a process such as chemical mechanicalpolishing (CMP) although any suitable removal process may be used.

Once the second semiconductor device 211 has been placed between thevias 209, the second semiconductor device 211 and the vias 209 may beencapsulated with a second encapsulant 213. The encapsulation may beperformed in a molding device (not individually illustrated in FIG. 2A).For example, the second semiconductor device 211 and the vias 209 may beplaced within a cavity of the molding device, and the cavity may behermetically sealed. The second encapsulant 213 may be placed within thecavity either before the cavity is hermetically sealed or else may beinjected into the cavity through an injection port. In an embodiment thesecond encapsulant 213 may be a molding compound resin such aspolyimide, PPS, PEEK, PES, a heat resistant crystal resin, combinationsof these, or the like.

Once the second encapsulant 213 has been placed into the molding cavitysuch that the second encapsulant 213 encapsulates the carrier substrate201, the vias 209, and the second semiconductor device 211, the secondencapsulant 213 may be cured in order to harden the second encapsulant213 for optimum protection. While the exact curing process is dependentat least in part on the particular material chosen for the secondencapsulant 213, in an embodiment in which molding compound is chosen asthe second encapsulant 213, the curing could occur through a processsuch as heating the second encapsulant 213 to between about 100° C. andabout 130° C., such as about 125° C. for about 60 sec to about 3000 sec,such as about 600 sec. Additionally, initiators and/or catalysts may beincluded within the second encapsulant 213 to better control the curingprocess.

However, as one having ordinary skill in the art will recognize, thecuring process described above is merely an exemplary process and is notmeant to limit the current embodiments. Other curing processes, such asirradiation or even allowing the second encapsulant 213 to harden atambient temperature, may alternatively be used. Any suitable curingprocess may be used, and all such processes are fully intended to beincluded within the scope of the embodiments discussed herein.

Once the second encapsulant 213 has been placed, the second encapsulant213 is thinned in order to expose the vias 209 and, optionally, thesecond semiconductor device 211 for further processing. The thinning maybe performed, e.g., using a mechanical grinding or chemical mechanicalpolishing (CMP) process whereby chemical etchants and abrasives areutilized to react and grind away the second encapsulant 213 and thesecond semiconductor device 211 until the vias 209 and the secondsemiconductor device 211 have been exposed. As such, the secondsemiconductor device 211 and the vias 209 may have a planar surface thatis also planar with the second encapsulant 213.

However, while the CMP process described above is presented as oneillustrative embodiment, it is not intended to be limiting to theembodiments. Any other suitable removal process may alternatively beused to thin the second encapsulant 213 and the second semiconductordevice 211 and expose the vias 209. For example, a series of chemicaletches may alternatively be utilized. This process and any othersuitable process may alternatively be utilized to thin the secondencapsulant 213 and the second semiconductor device 211, and all suchprocesses are fully intended to be included within the scope of theembodiments.

The first redistribution layer 215 is utilized to interconnect thesecond semiconductor device 211, the vias 209 and the first package 100(see FIG. 1). In an embodiment the first redistribution layer 215 isformed by initially forming a seed layer (not shown) of, e.g., atitanium copper alloy through a suitable formation process such as CVDor sputtering. A photoresist (also not shown) may then be formed tocover the seed layer, and the photoresist may then be patterned toexpose those portions of the seed layer that are located where the firstredistribution layer 215 is desired to be located.

Once the photoresist has been formed and patterned, a conductivematerial, such as copper, may be formed on the seed layer through adeposition process such as plating. The conductive material may beformed to have a thickness of between about 1 μm and about 10 μm, suchas about 5 μm, and a width of between about 5 μm and about 300 μm, suchas about 5 μm. However, while the material and methods discussed aresuitable to form the conductive material, these materials are merelyexemplary. Any other suitable materials, such as AlCu or Au, and anyother suitable processes of formation, such as CVD or PVD followed by apatterning process, may alternatively be used to form the firstredistribution layer 215.

Once the conductive material has been formed, the photoresist may beremoved through a suitable removal process such as ashing. Additionally,after the removal of the photoresist, those portions of the seed layerthat were covered by the photoresist may be removed through, forexample, a suitable etch process using the conductive material as amask.

Once the first redistribution layer 215 has been formed, second contactpads 217 are formed in order to electrically interconnect the firstredistribution layer 215 to, e.g., the second external connections 203.In an embodiment the second contact pads 217 are similar to the firstcontact pads 109 (described above with respect to FIG. 1), such as bybeing aluminum contact pads formed using a deposition process such assputtering and then patterned. However, the second contact pads 217 maybe formed from any suitable material and using any suitable process.

The first passivation layer 219 may be formed over the firstredistribution layer 215 and the second contact pads 217 in order toprovide protection and isolation for the first redistribution layer 215and the other underlying structures. In an embodiment the firstpassivation layer 219 may be polybenzoxazole (PBO), although anysuitable material, such as polyimide or a polyimide derivative, mayalternatively be utilized. The first passivation layer 219 may be placedusing, e.g., a spin-coating process to a thickness of between about 5 μmand about 25 μm, such as about 7 μm, although any suitable method andthickness may alternatively be used. Once in place, the second contactpads 217 may be exposed through the first passivation layer 219 beremoving a portion of the first passivation layer 219 through a processsuch as chemical mechanical polishing (CMP), although any suitableremoval process may alternatively be utilized.

The second external connections 203 are formed in connection with thesecond contact pads 217. In an embodiment the second externalconnections 203 are similar to the first external connections 113(described above with respect to FIG. 1), such as by being contact bumpssuch as microbumps or controlled collapse chip connection (C4) bumps.However, any other suitable type of electrical connection mayalternatively be utilized for the second external connections 203.

FIG. 2B illustrates further processing in the formation of the secondpackage 200. In an embodiment the carrier substrate 201 and the adhesivelayer 202 are debonded from the remainder of the structure using, e.g.,a thermal process to alter the adhesive properties of the adhesive layer202. In a particular embodiment an energy source such as an ultraviolet(UV) laser, a carbon dioxide (CO₂) laser, or an infrared (IR) laser, isutilized to irradiate and heat the adhesive layer 202 until the adhesivelayer 202 loses at least some of its adhesive properties. Onceperformed, the carrier substrate 201 and the adhesive layer 202 may bephysically separated and removed from the structure.

Additionally, once the carrier substrate 201 and the adhesive layer 202have been removed, the polymer layer 205 may be patterned in order toexpose the vias 209 and the second contact pads 227. In an embodimentthe polymer layer 205 is patterned by initially applying a photoresist(not individually illustrated in FIG. 2B) to the polymer layer 205 andthen exposing the photoresist to a patterned energy source (e.g., apatterned light source) so as to induce a chemical reaction, therebyinducing a physical change in those portions of the photoresist exposedto the patterned light source. A developer is then applied to theexposed photoresist to take advantage of the physical changes andselectively remove either the exposed portion of the photoresist or theunexposed portion of the photoresist, depending upon the desiredpattern, and the underlying exposed portion of the polymer layer 205 areremoved with, e.g., a dry etch process. However, any other suitablemethod for patterning the polymer layer 205 may alternatively beutilized.

FIG. 2B also illustrates a formation of third metallization layers 233in electrical connection with the vias 209 and the second contact pads227 in order to interconnect the vias 209 and the second contact pads227 with, e.g., an external device such as a second substrate 401 (notillustrated in FIG. 2B but illustrated and described below with respectto FIG. 4). The third metallization layers 233 are formed of alternatinglayers of dielectric material 235 and conductive material 237, whereinthe conductive material 237 is interconnected vertically with vias andmay be formed through any suitable process (such as deposition,damascene, dual damascene, etc.). In an embodiment there may be fourlayers of metallization, but the precise number of third metallizationlayers 233 is dependent upon the design of the second package 200.

In an embodiment the second metallization layers 223 is separated intothree distinct regions: a signal region 243, a power region 245, and aground region 247. The signal region 243, as its name suggests,comprises metallization and vias that work to carry signals to and fromthe vias 209 and the second semiconductor device 211. In an embodimentthe vias and metallization within the signal region 243 are designed andsized in order to provide a suitable routing for signals to and from thevias 209 and the second semiconductor device 211. For example, the viaswithin the signal region 243 may have a first diameter of between about5 μm and about 20 μm, such as about 20 μm, while the metallization mayhave a first thickness of between about 1.5 μm and about 5.0 μm, such asabout 2.0 μm. However, any other suitable dimensions may alternativelybe utilized.

The power region 245, as its name suggests, comprises metallization andvias that work to distribute power to the second semiconductor device211. In addition, the vias and metallization within the power region 245will also serve as a thermal conduit to remove heat from the secondsemiconductor device 211. As such, the vias and metallization within thepower region 245 may be sized differently from the vias andmetallization in the signal region 243 in order to accommodate theadditional heat transfer. In an embodiment the vias within the powerregion 245 may have a second diameter of between about 5 μm and about 75μm, such as about 60 μm, while the metallization may have a secondthickness of between about 1.5 μm and about 5 μm, such as about 2 μm.However, any other suitable dimensions may alternatively be utilized.

The ground region 247, as its name suggests, supplies a ground potentialfor the second semiconductor device 211. Additionally, in an embodimentthe ground region 247 also works in conjunction with the power region245 to remove heat from the second semiconductor device 211. As such,the vias and metallization within the ground region 247 may be sizedsimilarly to the vias and metallization within the power region 245,although they may be sized differently if desired.

Once the second metallization layers 223 have been formed, third contactpads 249 may be formed to provide an electrical connection between thethird metallization layers 233 and, e.g., the second substrate 401. Inan embodiment the third contact pads 249 are similar to the firstcontact pads 109 (described above with respect to FIG. 1). For example,the third contact pads 249 may be aluminum contact pads formed using adeposition and patterning process, although any other suitable processmay alternatively be utilized.

FIG. 3 illustrates a bonding of the first package 100 and the secondpackage 200. In an embodiment the first package 100 may be bonded to thesecond package 200 by initially aligning the first external connections113 and the second external connections 203. Once in contact, a reflowmay be performed to reflow the material of the first externalconnections 113 and the second external connections 203 to physicallyand electrically bond the first package 100 to the second package 200.However, any other suitable method of bonding, such as copper-copperbonding, may alternatively be utilized based upon the chosen structureof the first external connections 113 and the second externalconnections 203, and all such bonding methods are fully intended to beincluded within the scope of the embodiments.

FIG. 3 also illustrates the formation of third external connections 301in connection with the third contact pads 249. The third externalconnections 301 may be contact bumps such as a ball grid array, althoughany suitable shape and size, such as microbumps, C4 bumps, or the like,may alternatively be utilized. In an embodiment the third externalconnections 301 comprise a material such as tin, silver, or copper,although any other suitable material may alternatively be utilized. Inan embodiment in which the third external connections 301 are tin solderbumps, the third external connections 301 may be formed by initiallyforming a layer of tin through any suitable method such as evaporation,electroplating, printing, solder transfer, ball placement, etc, to athickness of, e.g., about 100 μm. Once a layer of tin has been formed onthe structure, a reflow is performed in order to shape the material intothe desired bump shape.

FIG. 4A illustrates a bonding of the second package 200 with a secondsubstrate 401 using both fourth external connections 405 as well asfifth external connections 403 (shown in FIG. 4A as already being bondedwith the third external connections 301). In an embodiment the secondsubstrate 401 may be, e.g., a printed circuit board that works tointerconnect various electrical components to each other in order toprovide a desired functionality for a user. Alternatively, the secondsubstrate 401 may be another substrate and comprises multiple conductivelayers (not individually illustrated), some of which are inter-layerswithin the second substrate 401. These layers may be etched into tracesof various widths and lengths and connected through inter-layer vias.Together, the lines and vias may form an electrical network to route DCpower, ground, and signals from one side of the second substrate 401 tothe other. Those of skill in the art will recognize the second substrate401 may be fabricated from an organic (laminate) material such asbismaleimide-triazine (BT), a polymer-based material such asliquid-crystal polymer (LCP), a ceramic material such as low-temperatureco-fired ceramic (LTCC), a silicon or glass interposer, or the like.Those of skill in the art will also recognize the conductive layers andvias may be formed from any suitable conductive material, such ascopper, aluminum, silver, gold, other metals, alloys, combinationthereof, and/or the like, and formed by any suitable technique, such aselectro-chemical plating (ECP), electroless plating, other depositionmethods such as sputtering, printing, and chemical vapor deposition(CVD) methods, or the like.

In some embodiments, the second substrate 401 may include electricalelements, such as resistors, capacitors, signal distribution circuitry,combinations of these, or the like. These electrical elements may beactive, passive, or a combination thereof. In other embodiments, thesecond substrate 401 is free from both active and passive electricalelements therein. All such combinations are fully intended to beincluded within the scope of the embodiments.

The second substrate 401 may comprise fourth contact pads 407 in orderto electrically connect the second substrate 401 to, e.g., the secondpackage 200. In an embodiment the fourth contact pads 407 may be similarto the first contact pads 109 (described above with respect to FIG. 1).For example, the fourth contact pads 407 may be aluminum contact padsformed by a deposition and patterning process. However, the fourthcontact pads 407 may alternatively be different from the first contactpads 109.

In an embodiment the fifth external connections 403 may be formed toprovide an external connection between the fourth contact pads 407 andthe third contact pads 249. The fifth external connections 403 may becontact bumps such as a ball grid array, although any suitable shape andsize, such as microbumps, C4 bumps, or the like, may alternatively beutilized. In an embodiment the fifth external connections 403 comprise amaterial such as tin, silver, or copper, although any other suitablematerial may alternatively be utilized. In an embodiment in which thefifth external connections 403 are tin solder bumps, the fifth externalconnections 403 may be formed by initially forming a layer of tinthrough any suitable method such as evaporation, electroplating,printing, solder transfer, ball placement, etc, to a thickness of, e.g.,about 100 μm. Once a layer of tin has been formed on the structure, areflow is performed in order to shape the material into the desired bumpshape.

The fourth external connections 405 are used for both electricalconnectivity as well as for thermal conductivity. As such, the fourthexternal connections 405 have different physical properties than thefifth external connections 403. In an embodiment, the fourth externalconnections 405 are a material with a higher thermal conductivity thanthe fifth external connections 403 that allow for heat to flow from thesecond semiconductor device 211, through the power region 245 and theground region 247, and through the fourth external connections 405. Thisallows for a better removal of heat from the second semiconductor device211.

In a particular embodiment the fourth external connections 405 comprisecopper, although any other suitably conductive (both electrical as wellas thermal) material, such as aluminum or gold, may alternatively beutilized. Additionally, in the embodiment disclosed in FIG. 4A, thefourth external connections 405 made of copper are shaped as a copperblock, with a third width W₃ of between about 0.2 mm and about 50.0 mm,such as about 1.0 mm, and a first depth D₁ (not illustrated in thecross-section of FIG. 4A but located so as to go into and out of thepage of FIG. 4A, as illustrated in FIG. 4B) of between about 0.2 mm andabout 50.0 mm, such as about 1.0 mm. The fourth external connections 405have a first height H₁ that is sufficient to electrically and thermallyinterconnect the fourth contact pads 407 to the third contact pads 249.As such, while the precise height dimensions of the first height H₁ areat least in part dependent upon the overall design of the device, in anembodiment the first height H₁ may be between about 0.1 mm and about 0.3mm, such as about 0.16 mm.

Alternatively, the fourth external connections 405 may be formed ofother materials than simply conductive blocks. Rather, any suitablyconductive (both electrically and thermally) type of material, such asconductive foil (e.g., copper foil) or conductive paste (e.g., copperpaste), may alternatively be utilized. All such materials are fullyintended to be included within the scope of the embodiments.

Additionally, the fourth external connections 405 are not limited by theblock shape as described above and in the figures. Rather, any suitableshapes, such as circles, polygons, and other irregular shapes, such as astar, a cross or a U-shape, may also be utilized. All such shapes arefully intended to be included within the scope of the embodiments.

In an embodiment in which the fourth external connections 405 are copperblocks, the fourth external connections 405 may be placed onto thefourth contact pads 407 by initially placing solder flux 409 onto thefourth contact pads 407. The solder flux 409 may be applied by brushing,spraying, a stencil, or other methods, as examples. The solder flux 409generally has an acidic component that removes oxide barriers, and anadhesive quality that helps to prevent an integrated circuit from movingduring the process. The solder flux 409 may be simultaneously placed onthe fourth external connections 405 connecting to both the fourthcontact pads 407 and the fifth external connections 403 (although theseare not illustrated in FIG. 4A for clarity), although, if desired, thesolder flux 409 may only be placed onto the fourth external connections405 connecting to the fourth contact pads 407, or any combinationsthereof.

However, while solder flux 409 is described as being used in thisembodiment, other types of materials may also be utilized to aid theconnection between the fourth external connections 405 and the fourthcontact pads 407. Any other suitable material, such as a solder paste,may alternatively be utilized. All such materials are fully intended tobe included within the scope of the embodiments.

Once the solder flux 409 is in place, the fourth external connections405 may be physically placed in contact with the solder flux 409 using,e.g., a pick and place operation, although any suitable placementmethodology may alternatively be utilized. Once the fourth externalconnections 405 are in place, additional solder flux 409 may be placedon the third contact pads 249 and a thermal process may be performed inorder to bond the fourth external connections 405 with the fourthcontact pads 407 and the third contact pads 249 in the power region 245and the ground region 247. In a particular embodiment the thermalprocess may be the reflow process described above to reflow the fifthexternal connections 403, although a separate thermal process mayalternatively be utilized. As such, the reflow process will reflow thefifth external connections 403 as well as bond the fourth externalconnections 405, the fourth contact pads 407, and the third contact pads249.

Alternatively, instead of being placed on the fourth contact pads 407,the fourth external connections 405 may be placed on the third contactpads 249 and then bonded to the fourth contact pads 407. Any suitableplacement of the fourth external connections 405 between the fourthcontact pads 407 and the third contact pads 249 may be utilized, and allsuch placements are fully intended to be included within the scope ofthe embodiments.

FIG. 4B illustrates an expanded top down view (with additional ones ofthe fifth external connections 403 illustrated) of the second substrate401, the fifth external connections 403 and the fourth externalconnections 405, with the second semiconductor device 211 illustrated asa dashed box for convenience. As can be seen in this embodiment, thefourth external connections 405 are located within a center of thesecond semiconductor device 211 (when viewed from this perspective),while the fifth external connections 403 surround the fourth externalconnections 405 to provide signal connectivity to the secondsemiconductor device 211.

FIG. 4C illustrates another embodiment in which the fourth externalconnections 405, instead of being a single block within the power region245 and a single block within the ground region 247, are insteadseparated into a plurality of blocks, thereby allowing for additionaldesign flexibility. Any suitable number of fourth external connections405 may be utilized, and all such numbers and combinations are fullyintended to be included within the scope of the embodiments.

FIG. 5 illustrates a flow of heat 501 from the second semiconductordevice 211 during, e.g., operation of the second semiconductor device211. In this embodiment, the heat is initially generated within thesecond semiconductor device 211, travels through the third metallizationlayers 233 within the power region 245 and the ground region 247,through the fourth external connections 405, through the fourth contactpads 407, to the second substrate 401, where it can be easily dispersed.By removing this heat from the second semiconductor device 211 quickly,there is less heat accumulation that can have detrimental effects suchas lowering the overall performance of the device to causing theindividual elements of the second semiconductor device 211 to expand atdifferent rates, causing undesired stresses through differences incoefficients of thermal expansion.

FIG. 6 illustrates another embodiment in which slots 601 are formedwithin the fourth external connections 405 in order to help compensatefor stresses within the fourth external connections 405 that will begenerated during removal of heat from the second semiconductor device211. In an embodiment the slots 601 are openings within the fourthexternal connections 405, and may be formed using a process such asmasking and plating during formation, photolithographic masking andetching after formation, or the like. In an embodiment the individualslots 601 may be formed to have a second depth D₂ of between about 0.1mm and about 0.3 mm, such as about 0.2 mm, and a fourth width W₄ ofbetween about 0.1 mm and about 0.3 mm, such as about 0.2 mm.

Additionally, while three slots 601 are illustrated in FIG. 6 withineach of the fourth external connections 405, this is intended to beillustrated and is not intended to be limiting to the embodiments.Rather, any suitable number of slots 601, such as between about 1 andabout 16, may alternatively be utilized. All suitable number andplacement of slots 601 are fully intended to be included within thescope of the embodiments.

FIG. 7 illustrates another embodiment in which the fourth externalconnections 405, rather than being a conductive block, is a conductiveball. In this embodiment, the fourth external connections 405 still havea different property from the fifth external connections 403, and maybe, e.g., copper balls. In such an embodiment, the fourth externalconnections 405 are placed on the fourth contact pads 407 in a similarfashion as described above with respect to FIG. 4A, and a thermalprocess such as a reflow is utilized to bond the fourth externalconnections 405 to the fourth contact pads 407 and the third contactpads 249.

FIG. 8 illustrates yet another embodiment in which the placement of thefourth external connections 405 and, therefore of the flow of heat 501(see FIG. 5) is not limited to the region directly beneath the secondsemiconductor device 211. Rather, the fourth external connections 405may be formed to be partially beneath the second semiconductor device211 and extending partially away from beneath the second semiconductordevice 211. Such a design allows for greater design flexibility whilestill allowing the flow of heat 501 to remove heat from the secondsemiconductor device.

FIG. 8 also illustrates another embodiment (used either separately or inconjunction with the embodiments discussed above) in which the fourthexternal connections 405 and, therefore of the flow of heat 501 (seeFIG. 5) is located completely removed from beneath the secondsemiconductor device 211. Such an embodiment allows for even greaterdesign flexibility while still retaining some of the advantages of thefourth external connections' 405 ability to remove heat from the secondsemiconductor device.

By utilizing the fourth external connections 405 in order to bothelectrically and thermally connect the second semiconductor device 211to the second substrate 401, a thermal removal path may be formed wheredesired while other connections, such as the fifth external connections403 may be utilized in areas where thermal issues are not as prevalent.Such a combination allows the heat to be removed from the secondsemiconductor device 211 faster during both startup (as the fourthexternal connections 405 will have a higher heat density) as well asduring continuous operation, when the second semiconductor device 211 isgenerating heat continuously (when the fourth external connections 405have a higher thermal conductance). Such a quick removal allows forfewer defects to occur from higher temperatures.

In accordance with an embodiment, a semiconductor device comprising afirst package comprising a first semiconductor die surrounded by anencapsulant and vias through the encapsulant and laterally removed fromthe first semiconductor die, is provided. A first substrate is bonded tothe first package with a first external connection and a second externalconnection, wherein the second external connection comprises a differentmaterial than the first external connection.

In accordance with another embodiment, a semiconductor device comprisingan integrated fan out package is provided. A first set of externalconnections is bonded to a first side of the integrated fan out package,and a second set of external connections is bonded to the first side ofthe integrated fan out package, wherein the second set of externalconnections has a higher thermal conductivity than the first set ofexternal connections.

In accordance with yet an embodiment, a method of manufacturing asemiconductor device comprising placing a first set of externalconnections on a first side of an integrated fan out package isprovided. A second set of external connections is placed on the firstside of the integrated fan out package, wherein the second set ofexternal connections has a higher thermal conductivity than the firstset of external connections. A substrate is bonded to the second set ofexternal connections and the first set of external connections.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A semiconductor device comprising: an integratedfan out package comprising an embedded die and a redistributionstructure electrically coupled to the embedded die; a first set ofexternal connections bonded to a first side of the redistributionstructure of the integrated fan out package; and a second set ofexternal connections bonded to the first side of the redistributionstructure of the integrated fan out package, wherein the second set ofexternal connections has a higher thermal conductivity than the firstset of external connections, wherein the second set of externalconnections are laterally separated from the first set of externalconnections, wherein each of the first set of external connections andsecond set of external connections protrudes from the redistributionstructure of the integrated fan out package.
 2. The semiconductor deviceof claim 1, further comprising a first substrate bonded to the first setof external connections and the second set of external connections. 3.The semiconductor device of claim 2, further comprising a secondsubstrate bonded to the integrated fan out package on an opposite sideof the integrated fan out package than the first substrate.
 4. Thesemiconductor device of claim 1, wherein the first set of externalconnections comprises solder balls and the second set of externalconnections comprises copper blocks.
 5. The semiconductor device ofclaim 1, wherein the first set of external connections comprises solderballs and the second set of external connections comprises copper foil.6. The semiconductor device of claim 1, wherein the first set ofexternal connections comprises solder balls and the second set ofexternal connections comprises copper paste.
 7. The semiconductor deviceof claim 1, further comprising slots located within the second set ofexternal connections.
 8. A semiconductor device comprising: a firstsemiconductor device having a top surface and a bottom surface; firstexternal connections on the bottom surface of the first semiconductordevice, the first external connections electrically and physicallycoupled to first outermost contact pads of the bottom surface of thefirst semiconductor device; second external connections on the bottomsurface of the first semiconductor device, the second externalconnections electrically and physically coupled to second outermostcontact pads of the bottom surface of the first semiconductor device,the second external connections being larger than the first externalconnections, the second external connections comprising a differentconductive material than the first external connections; a firstsubstrate electrically and physically coupled to the first semiconductordevice by the first external connections and the second externalconnections; and a second substrate physically coupled to the firstsemiconductor device at the top surface, the first external connectionselectrically coupling the second substrate to the first substrate. 9.The semiconductor device of claim 8, wherein the first semiconductordevice is an integrated fan-out package.
 10. The semiconductor device ofclaim 8, wherein the first substrate is an interposer.
 11. Thesemiconductor device of claim 8, wherein the second substrate is aprinted circuit board.
 12. A semiconductor device comprising: anintegrated fan out package comprising a first semiconductor device; afirst set of external connections bonded to a first side of theintegrated fan out package; a second set of external connections bondedto the first side of the integrated fan out package, wherein the secondset of external connections has a higher thermal conductivity than thefirst set of external connections, wherein the second set of externalconnections are laterally separated from the first set of externalconnections, wherein a first connection of the first set of externalconnections has an uppermost surface which is level with an uppermostsurface of a second connection of the second set of externalconnections; and a first substrate bonded to the first set of externalconnections and the second set of external connections.
 13. Thesemiconductor device of claim 12, further comprising a second substratebonded to the integrated fan out package on an opposite side of theintegrated fan out package than the first substrate.
 14. Thesemiconductor device of claim 13, wherein the second substrate is aprinted circuit board.
 15. The semiconductor device of claim 13, whereinthe first set of external connections comprises solder balls and thesecond set of external connections comprises copper blocks, copper foil,or copper paste.
 16. The semiconductor device of claim 13, furthercomprising slots located within the second set of external connections.17. The semiconductor device of claim 12, wherein the first set ofexternal connections comprises solder balls and the second set ofexternal connections comprises copper blocks, wherein each of the secondset of external connections are within lateral extents of the firstsemiconductor device.
 18. The semiconductor device of claim 12, whereinthe first set of external connections comprises solder balls and thesecond set of external connections comprises copper foil.
 19. Thesemiconductor device of claim 12, wherein the first set of externalconnections comprises solder balls and the second set of externalconnections comprises copper paste.
 20. The semiconductor device ofclaim 12, further comprising slots located within the second set ofexternal connections.